Arachidonic acid (AA) was used to induce contractions of guinea-pig tracheal and lung parenchymal preparations in the presence of indomethacin. Prior addition of FPL55712, nordihydroguaiaretic acid (NDGA), piriprost, benoxaprofen or nafazatrom, in order of potency, inhibited AA-induced contractions of trachea. Higher concentrations (2 - 3 fold) were necessary to inhibit contractions of parenchyma. FPL55712 and piriprost appeared to act as pharmacological antagonists of leukotrienes because they rapidly reduced the tone of the airways established by AA. Administration of exogenous AA to indomethacin-treated trachea appears to be a good model to examine leukotriene receptor antagonists and inhibitors of the lipoxygenase pathway.